Merge pull request #850 from smoogipooo/mania-holdnote-input

Mania holdnote input

osu-framework

@@ -1 +1 @@
-Subproject commit 0b9053ec3d39b486165992374752b280c5eeef06
+Subproject commit aa3e296968873208ca4460b00c0b82fe3aa8ff5c

osu.Desktop.VisualTests/Tests/TestCaseManiaPlayfield.cs

@@ -11,6 +11,9 @@ using OpenTK;
 using osu.Game.Rulesets.Mania.Objects.Drawables;
 using osu.Game.Rulesets.Mania.Objects;
 using osu.Game.Rulesets.Mania.Timing;
+using osu.Framework.Configuration;
+using OpenTK.Input;
+using osu.Framework.Timing;
 
 namespace osu.Desktop.VisualTests.Tests
 {
@@ -59,6 +62,51 @@ namespace osu.Desktop.VisualTests.Tests
                 }
             };
 
+            Action createPlayfieldWithNotesAcceptingInput = () =>
+            {
+                Clear();
+
+                var rateAdjustClock = new StopwatchClock(true) { Rate = 0.5 };
+
+                ManiaPlayfield playField;
+                Add(playField = new ManiaPlayfield(4, new List<TimingChange> { new TimingChange { BeatLength = 200 } })
+                {
+                    Anchor = Anchor.Centre,
+                    Origin = Anchor.Centre,
+                    Scale = new Vector2(1, -1),
+                    Clock = new FramedClock(rateAdjustClock)
+                });
+
+                for (int t = 1000; t <= 2000; t += 100)
+                {
+                    playField.Add(new DrawableNote(new Note
+                    {
+                        StartTime = t,
+                        Column = 0
+                    }, new Bindable<Key>(Key.D)));
+
+                    playField.Add(new DrawableNote(new Note
+                    {
+                        StartTime = t,
+                        Column = 3
+                    }, new Bindable<Key>(Key.K)));
+                }
+
+                playField.Add(new DrawableHoldNote(new HoldNote
+                {
+                    StartTime = 1000,
+                    Duration = 1000,
+                    Column = 1
+                }, new Bindable<Key>(Key.F)));
+
+                playField.Add(new DrawableHoldNote(new HoldNote
+                {
+                    StartTime = 1000,
+                    Duration = 1000,
+                    Column = 2
+                }, new Bindable<Key>(Key.J)));
+            };
+
             AddStep("1 column", () => createPlayfield(1, SpecialColumnPosition.Normal));
             AddStep("4 columns", () => createPlayfield(4, SpecialColumnPosition.Normal));
             AddStep("Left special style", () => createPlayfield(4, SpecialColumnPosition.Left));
@@ -76,6 +124,8 @@ namespace osu.Desktop.VisualTests.Tests
             AddWaitStep(10);
             AddStep("Right special style", () => createPlayfieldWithNotes(4, SpecialColumnPosition.Right));
             AddWaitStep(10);
+
+            AddStep("Notes with input", () => createPlayfieldWithNotesAcceptingInput());
         }
 
         private void triggerKeyDown(Column column)

osu.Game.Rulesets.Mania/Beatmaps/Patterns/Legacy/DistanceObjectPatternGenerator.cs

@@ -471,14 +471,17 @@ namespace osu.Game.Rulesets.Mania.Beatmaps.Patterns.Legacy
             }
             else
             {
-                newObject = new HoldNote
+                var holdNote = new HoldNote
                 {
                     StartTime = startTime,
-                    Samples = sampleInfoListAt(startTime),
-                    EndSamples = sampleInfoListAt(endTime),
                     Column = column,
-                    Duration = endTime - startTime
+                    Duration = endTime - startTime,
+                    Head = { Samples = sampleInfoListAt(startTime) },
+                    Tail = { Samples = sampleInfoListAt(endTime) }
                 };
+
+
+                newObject = holdNote;
             }
 
             pattern.Add(newObject);

osu.Game.Rulesets.Mania/Beatmaps/Patterns/Legacy/EndTimeObjectPatternGenerator.cs

@@ -69,18 +69,21 @@ namespace osu.Game.Rulesets.Mania.Beatmaps.Patterns.Legacy
 
             if (holdNote)
             {
-                newObject = new HoldNote
+                var hold = new HoldNote
                 {
                     StartTime = HitObject.StartTime,
-                    EndSamples = HitObject.Samples,
                     Column = column,
                     Duration = endTime - HitObject.StartTime
                 };
 
-                newObject.Samples.Add(new SampleInfo
+                hold.Head.Samples.Add(new SampleInfo
                 {
                     Name = SampleInfo.HIT_NORMAL
                 });
+
+                hold.Tail.Samples = HitObject.Samples;
+
+                newObject = hold;
             }
             else
             {

osu.Game.Rulesets.Mania/Judgements/HoldNoteTailJudgement.cs

@@ -0,0 +1,13 @@
+// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+namespace osu.Game.Rulesets.Mania.Judgements
+{
+    public class HoldNoteTailJudgement : ManiaJudgement
+    {
+        /// <summary>
+        /// Whether the hold note has been released too early and shouldn't give full score for the release.
+        /// </summary>
+        public bool HasBroken;
+    }
+}

osu.Game.Rulesets.Mania/Judgements/HoldNoteTickJudgement.cs

@@ -0,0 +1,9 @@
+// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+namespace osu.Game.Rulesets.Mania.Judgements
+{
+    public class HoldNoteTickJudgement : ManiaJudgement
+    {
+    }
+}

osu.Game.Rulesets.Mania/Objects/Drawables/DrawableHoldNote.cs

@@ -7,14 +7,34 @@ using osu.Game.Rulesets.Mania.Objects.Drawables.Pieces;
 using OpenTK.Graphics;
 using osu.Framework.Configuration;
 using OpenTK.Input;
+using osu.Framework.Input;
+using OpenTK;
+using osu.Framework.Graphics.Containers;
+using osu.Game.Rulesets.Mania.Judgements;
+using osu.Framework.Extensions.IEnumerableExtensions;
 
 namespace osu.Game.Rulesets.Mania.Objects.Drawables
 {
+    /// <summary>
+    /// Visualises a <see cref="HoldNote"/> hit object.
+    /// </summary>
     public class DrawableHoldNote : DrawableManiaHitObject<HoldNote>
     {
-        private readonly NotePiece headPiece;
+        private readonly DrawableNote head;
+        private readonly DrawableNote tail;
+
         private readonly BodyPiece bodyPiece;
-        private readonly NotePiece tailPiece;
+        private readonly Container<DrawableHoldNoteTick> tickContainer;
+
+        /// <summary>
+        /// Time at which the user started holding this hold note. Null if the user is not holding this hold note.
+        /// </summary>
+        private double? holdStartTime;
+
+        /// <summary>
+        /// Whether the hold note has been released too early and shouldn't give full score for the release.
+        /// </summary>
+        private bool hasBroken;
 
         public DrawableHoldNote(HoldNote hitObject, Bindable<Key> key = null)
             : base(hitObject, key)
@@ -32,17 +52,39 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
                     Anchor = Anchor.TopCentre,
                     Origin = Anchor.TopCentre,
                 },
-                headPiece = new NotePiece
+                tickContainer = new Container<DrawableHoldNoteTick>
+                {
+                    RelativeSizeAxes = Axes.Both,
+                    RelativeCoordinateSpace = new Vector2(1, (float)HitObject.Duration)
+                },
+                head = new DrawableHeadNote(this, key)
                 {
                     Anchor = Anchor.TopCentre,
                     Origin = Anchor.TopCentre
                 },
-                tailPiece = new NotePiece
+                tail = new DrawableTailNote(this, key)
                 {
                     Anchor = Anchor.BottomCentre,
                     Origin = Anchor.TopCentre
                 }
             });
+
+            foreach (var tick in HitObject.Ticks)
+            {
+                var drawableTick = new DrawableHoldNoteTick(tick)
+                {
+                    HoldStartTime = () => holdStartTime
+                };
+
+                // To make the ticks relative to ourselves we need to offset them backwards
+                drawableTick.Y -= (float)HitObject.StartTime;
+
+                tickContainer.Add(drawableTick);
+                AddNested(drawableTick);
+            }
+
+            AddNested(head);
+            AddNested(tail);
         }
 
         public override Color4 AccentColour
@@ -54,9 +96,11 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
                     return;
                 base.AccentColour = value;
 
-                headPiece.AccentColour = value;
+                tickContainer.Children.ForEach(t => t.AccentColour = value);
+
                 bodyPiece.AccentColour = value;
-                tailPiece.AccentColour = value;
+                head.AccentColour = value;
+                tail.AccentColour = value;
             }
         }
 
@@ -64,14 +108,132 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
         {
         }
 
-        protected override void Update()
+        protected override bool OnKeyDown(InputState state, KeyDownEventArgs args)
         {
-            if (Time.Current > HitObject.StartTime)
+            // Make sure the keypress happened within the body of the hold note
-                headPiece.Colour = Color4.Green;
+            if (Time.Current < HitObject.StartTime || Time.Current > HitObject.EndTime)
-            if (Time.Current > HitObject.EndTime)
+                return false;
+
+            if (args.Key != Key)
+                return false;
+
+            if (args.Repeat)
+                return false;
+
+            // The user has pressed during the body of the hold note, after the head note and its hit windows have passed
+            // and within the limited range of the above if-statement. This state will be managed by the head note if the
+            // user has pressed during the hit windows of the head note.
+            holdStartTime = Time.Current;
+
+            return true;
+        }
+
+        protected override bool OnKeyUp(InputState state, KeyUpEventArgs args)
+        {
+            // Make sure that the user started holding the key during the hold note
+            if (!holdStartTime.HasValue)
+                return false;
+
+            if (args.Key != Key)
+                return false;
+
+            holdStartTime = null;
+
+            // If the key has been released too early, the user should not receive full score for the release
+            if (!tail.Judged)
+                hasBroken = true;
+
+            return true;
+        }
+
+        /// <summary>
+        /// The head note of a hold.
+        /// </summary>
+        private class DrawableHeadNote : DrawableNote
+        {
+            private readonly DrawableHoldNote holdNote;
+
+            public DrawableHeadNote(DrawableHoldNote holdNote, Bindable<Key> key = null)
+                : base(holdNote.HitObject.Head, key)
             {
-                bodyPiece.Colour = Color4.Green;
+                this.holdNote = holdNote;
-                tailPiece.Colour = Color4.Green;
+
+                RelativePositionAxes = Axes.None;
+                Y = 0;
+            }
+
+            protected override bool OnKeyDown(InputState state, KeyDownEventArgs args)
+            {
+                if (!base.OnKeyDown(state, args))
+                    return false;
+
+                // We only want to trigger a holding state from the head if the head has received a judgement
+                if (!Judged)
+                    return false;
+
+                // If the key has been released too early, the user should not receive full score for the release
+                if (Judgement.Result == HitResult.Miss)
+                    holdNote.hasBroken = true;
+
+                // The head note also handles early hits before the body, but we want accurate early hits to count as the body being held
+                // The body doesn't handle these early early hits, so we have to explicitly set the holding state here
+                holdNote.holdStartTime = Time.Current;
+
+                return true;
+            }
+        }
+
+        /// <summary>
+        /// The tail note of a hold.
+        /// </summary>
+        private class DrawableTailNote : DrawableNote
+        {
+            private readonly DrawableHoldNote holdNote;
+
+            public DrawableTailNote(DrawableHoldNote holdNote, Bindable<Key> key = null)
+                : base(holdNote.HitObject.Tail, key)
+            {
+                this.holdNote = holdNote;
+
+                RelativePositionAxes = Axes.None;
+                Y = 0;
+            }
+
+            protected override ManiaJudgement CreateJudgement() => new HoldNoteTailJudgement();
+
+            protected override void CheckJudgement(bool userTriggered)
+            {
+                base.CheckJudgement(userTriggered);
+
+                var tailJudgement = Judgement as HoldNoteTailJudgement;
+                if (tailJudgement == null)
+                    return;
+
+                tailJudgement.HasBroken = holdNote.hasBroken;
+            }
+
+            protected override bool OnKeyUp(InputState state, KeyUpEventArgs args)
+            {
+                // Make sure that the user started holding the key during the hold note
+                if (!holdNote.holdStartTime.HasValue)
+                    return false;
+
+                if (Judgement.Result != HitResult.None)
+                    return false;
+
+                if (args.Key != Key)
+                    return false;
+
+                UpdateJudgement(true);
+
+                // Handled by the hold note, which will set holding = false
+                return false;
+            }
+
+            protected override bool OnKeyDown(InputState state, KeyDownEventArgs args)
+            {
+                // Tail doesn't handle key down
+                return false;
             }
         }
     }

osu.Game.Rulesets.Mania/Objects/Drawables/DrawableHoldNoteTick.cs

@@ -0,0 +1,121 @@
+// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using System;
+using OpenTK;
+using OpenTK.Graphics;
+using osu.Framework.Extensions.Color4Extensions;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Sprites;
+using osu.Game.Rulesets.Mania.Judgements;
+using osu.Game.Rulesets.Objects.Drawables;
+
+namespace osu.Game.Rulesets.Mania.Objects.Drawables
+{
+    /// <summary>
+    /// Visualises a <see cref="HoldNoteTick"/> hit object.
+    /// </summary>
+    public class DrawableHoldNoteTick : DrawableManiaHitObject<HoldNoteTick>
+    {
+        /// <summary>
+        /// References the time at which the user started holding the hold note.
+        /// </summary>
+        public Func<double?> HoldStartTime;
+
+        /// <summary>
+        /// References whether the user is currently holding the hold note.
+        /// </summary>
+        public Func<bool> IsHolding;
+
+        private readonly Container glowContainer;
+
+        public DrawableHoldNoteTick(HoldNoteTick hitObject)
+            : base(hitObject)
+        {
+            Anchor = Anchor.TopCentre;
+            Origin = Anchor.TopCentre;
+
+            RelativeSizeAxes = Axes.X;
+            Size = new Vector2(1);
+
+            Children = new[]
+            {
+                glowContainer = new CircularContainer
+                {
+                    Anchor = Anchor.TopCentre,
+                    Origin = Anchor.TopCentre,
+                    RelativeSizeAxes = Axes.Both,
+                    Masking = true,
+                    Children = new[]
+                    {
+                        new Box
+                        {
+                            RelativeSizeAxes = Axes.Both,
+                            Alpha = 0,
+                            AlwaysPresent = true
+                        }
+                    }
+                }
+            };
+
+            // Set the default glow
+            AccentColour = Color4.White;
+        }
+
+        public override Color4 AccentColour
+        {
+            get { return base.AccentColour; }
+            set
+            {
+                base.AccentColour = value;
+
+                glowContainer.EdgeEffect = new EdgeEffect
+                {
+                    Type = EdgeEffectType.Glow,
+                    Radius = 2f,
+                    Roundness = 15f,
+                    Colour = value.Opacity(0.3f)
+                };
+            }
+        }
+
+        protected override ManiaJudgement CreateJudgement() => new HoldNoteTickJudgement();
+
+        protected override void CheckJudgement(bool userTriggered)
+        {
+            if (!userTriggered)
+                return;
+
+            if (Time.Current < HitObject.StartTime)
+                return;
+
+            if (HoldStartTime?.Invoke() > HitObject.StartTime)
+                return;
+
+            Judgement.ManiaResult = ManiaHitResult.Perfect;
+            Judgement.Result = HitResult.Hit;
+        }
+
+        protected override void UpdateState(ArmedState state)
+        {
+            switch (State)
+            {
+                case ArmedState.Hit:
+                    AccentColour = Color4.Green;
+                    break;
+            }
+        }
+
+        protected override void Update()
+        {
+            if (Judgement.Result != HitResult.None)
+                return;
+
+            if (IsHolding?.Invoke() != true)
+                return;
+
+            UpdateJudgement(true);
+        }
+    }
+}

osu.Game.Rulesets.Mania/Objects/Drawables/DrawableNote.cs

@@ -13,6 +13,9 @@ using osu.Game.Rulesets.Objects.Drawables;
 
 namespace osu.Game.Rulesets.Mania.Objects.Drawables
 {
+    /// <summary>
+    /// Visualises a <see cref="Note"/> hit object.
+    /// </summary>
     public class DrawableNote : DrawableManiaHitObject<Note>
     {
         private readonly NotePiece headPiece;

osu.Game.Rulesets.Mania/Objects/HoldNote.cs

@@ -1,10 +1,9 @@
 // Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
 // Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
-using osu.Game.Audio;
+using System.Collections.Generic;
 using osu.Game.Beatmaps.ControlPoints;
 using osu.Game.Database;
-using osu.Game.Rulesets.Mania.Judgements;
 using osu.Game.Rulesets.Objects.Types;
 
 namespace osu.Game.Rulesets.Mania.Objects
@@ -12,32 +11,96 @@ namespace osu.Game.Rulesets.Mania.Objects
     /// <summary>
     /// Represents a hit object which requires pressing, holding, and releasing a key.
     /// </summary>
-    public class HoldNote : Note, IHasEndTime
+    public class HoldNote : ManiaHitObject, IHasEndTime
     {
-        /// <summary>
-        /// Lenience of release hit windows. This is to make cases where the hold note release
-        /// is timed alongside presses of other hit objects less awkward.
-        /// </summary>
-        private const double release_window_lenience = 1.5;
-
-        public double Duration { get; set; }
         public double EndTime => StartTime + Duration;
 
-        /// <summary>
+        private double duration;
-        /// The samples to be played when this hold note is released.
+        public double Duration
-        /// </summary>
+        {
-        public SampleInfoList EndSamples = new SampleInfoList();
+            get { return duration; }
+            set
+            {
+                duration = value;
+                Tail.StartTime = EndTime;
+            }
+        }
+
+        public override double StartTime
+        {
+            get { return base.StartTime; }
+            set
+            {
+                base.StartTime = value;
+                Head.StartTime = value;
+                Tail.StartTime = EndTime;
+            }
+        }
 
         /// <summary>
-        /// The key-release hit windows for this hold note.
+        /// The head note of the hold.
         /// </summary>
-        public HitWindows ReleaseHitWindows { get; protected set; } = new HitWindows();
+        public readonly Note Head = new Note();
+
+        /// <summary>
+        /// The tail note of the hold.
+        /// </summary>
+        public readonly Note Tail = new TailNote();
+
+        /// <summary>
+        /// The time between ticks of this hold.
+        /// </summary>
+        private double tickSpacing = 50;
 
         public override void ApplyDefaults(ControlPointInfo controlPointInfo, BeatmapDifficulty difficulty)
         {
             base.ApplyDefaults(controlPointInfo, difficulty);
 
-            ReleaseHitWindows = HitWindows * release_window_lenience;
+            TimingControlPoint timingPoint = controlPointInfo.TimingPointAt(StartTime);
+            tickSpacing = timingPoint.BeatLength / difficulty.SliderTickRate;
+        }
+
+        /// <summary>
+        /// The scoring scoring ticks of the hold note.
+        /// </summary>
+        public IEnumerable<HoldNoteTick> Ticks => ticks ?? (ticks = createTicks());
+        private List<HoldNoteTick> ticks;
+
+        private List<HoldNoteTick> createTicks()
+        {
+            var ret = new List<HoldNoteTick>();
+
+            if (tickSpacing == 0)
+                return ret;
+
+            for (double t = StartTime + tickSpacing; t <= EndTime - tickSpacing; t += tickSpacing)
+            {
+                ret.Add(new HoldNoteTick
+                {
+                    StartTime = t
+                });
+            }
+
+            return ret;
+        }
+
+        /// <summary>
+        /// The tail of the hold note.
+        /// </summary>
+        private class TailNote : Note
+        {
+            /// <summary>
+            /// Lenience of release hit windows. This is to make cases where the hold note release
+            /// is timed alongside presses of other hit objects less awkward.
+            /// </summary>
+            private const double release_window_lenience = 1.5;
+
+            public override void ApplyDefaults(ControlPointInfo controlPointInfo, BeatmapDifficulty difficulty)
+            {
+                base.ApplyDefaults(controlPointInfo, difficulty);
+
+                HitWindows *= release_window_lenience;
+            }
         }
     }
 }

osu.Game.Rulesets.Mania/Objects/HoldNoteTick.cs

@@ -0,0 +1,12 @@
+// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+namespace osu.Game.Rulesets.Mania.Objects
+{
+    /// <summary>
+    /// A scoring tick of a hold note.
+    /// </summary>
+    public class HoldNoteTick : ManiaHitObject
+    {
+    }
+}

osu.Game.Rulesets.Mania/Timing/ControlPointContainer.cs

@@ -8,6 +8,7 @@ using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using OpenTK;
 using osu.Game.Beatmaps.ControlPoints;
+using osu.Game.Rulesets.Objects;
 
 namespace osu.Game.Rulesets.Mania.Timing
 {
@@ -128,6 +129,8 @@ namespace osu.Game.Rulesets.Mania.Timing
             /// </summary>
             private class AutoTimeRelativeContainer : Container
             {
+                protected override IComparer<Drawable> DepthComparer => new HitObjectReverseStartTimeComparer();
+
                 public override void InvalidateFromChild(Invalidation invalidation)
                 {
                     // We only want to re-compute our size when a child's size or position has changed

osu.Game.Rulesets.Mania/UI/Column.cs

@@ -1,7 +1,6 @@
 // Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
 // Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
-
 using OpenTK;
 using OpenTK.Graphics;
 using OpenTK.Input;
@@ -188,7 +187,11 @@ namespace osu.Game.Rulesets.Mania.UI
             }
         }
 
-        public void Add(DrawableHitObject<ManiaHitObject, ManiaJudgement> hitObject) => ControlPointContainer.Add(hitObject);
+        public void Add(DrawableHitObject<ManiaHitObject, ManiaJudgement> hitObject)
+        {
+            hitObject.AccentColour = AccentColour;
+            ControlPointContainer.Add(hitObject);
+        }
 
         private bool onKeyDown(InputState state, KeyDownEventArgs args)
         {

osu.Game.Rulesets.Mania/osu.Game.Rulesets.Mania.csproj

@@ -57,10 +57,13 @@
     <Compile Include="Beatmaps\Patterns\Pattern.cs" />
     <Compile Include="MathUtils\FastRandom.cs" />
     <Compile Include="Judgements\HitWindows.cs" />
+    <Compile Include="Judgements\HoldNoteTailJudgement.cs" />
+    <Compile Include="Judgements\HoldNoteTickJudgement.cs" />
     <Compile Include="Judgements\ManiaHitResult.cs" />
     <Compile Include="Judgements\ManiaJudgement.cs" />
     <Compile Include="ManiaDifficultyCalculator.cs" />
     <Compile Include="Objects\Drawables\DrawableHoldNote.cs" />
+    <Compile Include="Objects\Drawables\DrawableHoldNoteTick.cs" />
     <Compile Include="Objects\Drawables\DrawableManiaHitObject.cs" />
     <Compile Include="Objects\Drawables\DrawableNote.cs" />
     <Compile Include="Objects\Drawables\Pieces\BodyPiece.cs" />
@@ -68,6 +71,7 @@
     <Compile Include="Objects\Types\IHasColumn.cs" />
     <Compile Include="Scoring\ManiaScoreProcessor.cs" />
     <Compile Include="Objects\HoldNote.cs" />
+    <Compile Include="Objects\HoldNoteTick.cs" />
     <Compile Include="Objects\ManiaHitObject.cs" />
     <Compile Include="Objects\Note.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />

osu.Game/Rulesets/Objects/Drawables/DrawableHitObject.cs

@@ -15,28 +15,51 @@ using System.Linq;
 
 namespace osu.Game.Rulesets.Objects.Drawables
 {
-    public abstract class DrawableHitObject<TObject, TJudgement> : Container
+    public abstract class DrawableHitObject : Container
-        where TObject : HitObject
-        where TJudgement : Judgement
     {
-        public event Action<DrawableHitObject<TObject, TJudgement>> OnJudgement;
+        public readonly HitObject HitObject;
-
-        public TObject HitObject;
 
         /// <summary>
         /// The colour used for various elements of this DrawableHitObject.
         /// </summary>
         public virtual Color4 AccentColour { get; set; }
 
+        protected DrawableHitObject(HitObject hitObject)
+        {
+            HitObject = hitObject;
+        }
+    }
+
+    public abstract class DrawableHitObject<TObject> : DrawableHitObject
+        where TObject : HitObject
+    {
+        public new readonly TObject HitObject;
+
+        protected DrawableHitObject(TObject hitObject)
+            : base(hitObject)
+        {
+            HitObject = hitObject;
+        }
+    }
+
+    public abstract class DrawableHitObject<TObject, TJudgement> : DrawableHitObject<TObject>
+        where TObject : HitObject
+        where TJudgement : Judgement
+    {
+        public event Action<DrawableHitObject<TObject, TJudgement>> OnJudgement;
+
         public override bool HandleInput => Interactive;
 
         public bool Interactive = true;
 
         public TJudgement Judgement;
 
-        protected abstract TJudgement CreateJudgement();
+        protected List<SampleChannel> Samples = new List<SampleChannel>();
 
-        protected abstract void UpdateState(ArmedState state);
+        protected DrawableHitObject(TObject hitObject)
+            : base(hitObject)
+        {
+        }
 
         private ArmedState state;
         public ArmedState State
@@ -59,8 +82,6 @@ namespace osu.Game.Rulesets.Objects.Drawables
             }
         }
 
-        protected List<SampleChannel> Samples = new List<SampleChannel>();
-
         protected void PlaySamples()
         {
             Samples.ForEach(s => s?.Play());
@@ -79,11 +100,6 @@ namespace osu.Game.Rulesets.Objects.Drawables
         /// </summary>
         public bool Judged => (Judgement?.Result ?? HitResult.None) != HitResult.None && (NestedHitObjects?.All(h => h.Judged) ?? true);
 
-        protected DrawableHitObject(TObject hitObject)
-        {
-            HitObject = hitObject;
-        }
-
         /// <summary>
         /// Process a hit of this hitobject. Carries out judgement.
         /// </summary>
@@ -176,5 +192,8 @@ namespace osu.Game.Rulesets.Objects.Drawables
             h.OnJudgement += d => OnJudgement?.Invoke(d);
             nestedHitObjects.Add(h);
         }
+
+        protected abstract TJudgement CreateJudgement();
+        protected abstract void UpdateState(ArmedState state);
     }
 }

osu.Game/Rulesets/Objects/HitObject.cs

@@ -19,7 +19,7 @@ namespace osu.Game.Rulesets.Objects
         /// <summary>
         /// The time at which the HitObject starts.
         /// </summary>
-        public double StartTime;
+        public virtual double StartTime { get; set; }
 
         /// <summary>
         /// The samples to be played when this hit object is hit.

osu.Game/Rulesets/Objects/HitObjectStartTimeComparer.cs

@@ -0,0 +1,55 @@
+// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using osu.Framework.Graphics;
+using osu.Game.Rulesets.Objects.Drawables;
+
+namespace osu.Game.Rulesets.Objects
+{
+    /// <summary>
+    /// Compares two hit objects by their start time, falling back to creation order if their start time is equal.
+    /// </summary>
+    public class HitObjectStartTimeComparer : Drawable.CreationOrderDepthComparer
+    {
+        public override int Compare(Drawable x, Drawable y)
+        {
+            var hitObjectX = x as DrawableHitObject;
+            var hitObjectY = y as DrawableHitObject;
+
+            // If either of the two drawables are not hit objects, fall back to the base comparer
+            if (hitObjectX?.HitObject == null || hitObjectY?.HitObject == null)
+                return base.Compare(x, y);
+
+            // Compare by start time
+            int i = hitObjectX.HitObject.StartTime.CompareTo(hitObjectY.HitObject.StartTime);
+            if (i != 0)
+                return i;
+
+            return base.Compare(x, y);
+        }
+    }
+
+    /// <summary>
+    /// Compares two hit objects by their start time, falling back to creation order if their start time is equal.
+    /// This will compare the two hit objects in reverse order.
+    /// </summary>
+    public class HitObjectReverseStartTimeComparer : Drawable.ReverseCreationOrderDepthComparer
+    {
+        public override int Compare(Drawable x, Drawable y)
+        {
+            var hitObjectX = x as DrawableHitObject;
+            var hitObjectY = y as DrawableHitObject;
+
+            // If either of the two drawables are not hit objects, fall back to the base comparer
+            if (hitObjectX?.HitObject == null || hitObjectY?.HitObject == null)
+                return base.Compare(x, y);
+
+            // Compare by start time
+            int i = hitObjectY.HitObject.StartTime.CompareTo(hitObjectX.HitObject.StartTime);
+            if (i != 0)
+                return i;
+
+            return base.Compare(x, y);
+        }
+    }
+}

osu.Game/osu.Game.csproj

@@ -176,6 +176,7 @@
     <Compile Include="Rulesets\Objects\Drawables\IDrawableHitObjectWithProxiedApproach.cs" />
     <Compile Include="Rulesets\Judgements\Judgement.cs" />
     <Compile Include="Rulesets\Objects\HitObjectParser.cs" />
+    <Compile Include="Rulesets\Objects\HitObjectStartTimeComparer.cs" />
     <Compile Include="Rulesets\Objects\Types\IHasCombo.cs" />
     <Compile Include="Rulesets\Objects\Types\IHasEndTime.cs" />
     <Compile Include="Rulesets\Objects\Types\IHasDistance.cs" />